To obtain the vertical earth pressure on a soft foundation box culvert and investigate the interaction of the soil-culvert-foundation system, both a centrifugal model test and a numerical simulation were conducted and...To obtain the vertical earth pressure on a soft foundation box culvert and investigate the interaction of the soil-culvert-foundation system, both a centrifugal model test and a numerical simulation were conducted and the comparisons with the current methods to determine the load on a culvert were completed. The results of the model test and numerical analysis are in satisfactory agreement, which shows that the direction of the shear stress between the culvert and the adjacent embankment depends on the differential settlement between them. A vertical earth pressure concentration appears on the culvert with a rigid piles foundation because of a downward shear stress. The ratio of the load on a soft foundation culvert and the overburden pressure above the culvert raises first and then decreases as the backfill height increases. In order to reduce the load on a culvert, it is suggested to limit the stiffness difference of the foundations under the culvert and embankment and to use a light backfill over the culvert.展开更多
Studying the critical response characteristics of reinforced concrete box culverts with diverse geometrical configurations under seismic excitations is a necessary step to develop a reasonable design method. In this w...Studying the critical response characteristics of reinforced concrete box culverts with diverse geometrical configurations under seismic excitations is a necessary step to develop a reasonable design method. In this work, numerical analysis and assessment of reinforced concrete box culverts for seismic loading in addition to standard static loading from dead and live loads is conducted, aiming to highlight the critical difference in the seismic performances between two and three cell box culverts under near and far-fault ground motion. The results show how and where the seismic loading alters the responses of seismic loading of the models including the effect on safety and failure. The geometrical configurations of the culvert combined with the loading scenarios also significantly influence the magnitude and distribution of the seismic responses. The findings of this work shed light on the critical role of the geometrical configurations and shaking event in the seismic responses of reinforced concrete box culverts and this procedure can be applied as seismic assessment method to any culvert shape, size, and material.展开更多
To shorten the existing box culvert demolition construction period and ensure the normal operation of the railway, the jacking-out construction method was adopted. The ABAQUS finite element software was used to establ...To shorten the existing box culvert demolition construction period and ensure the normal operation of the railway, the jacking-out construction method was adopted. The ABAQUS finite element software was used to establish a three-dimensional model of the box culvert and soil body of the relying project, and three excavation thickness (0m, 1 m, 2 m) were used as the main variation parameters for numerical analysis and research, and the change law of the box culvert itself and soil body stress during the culvert jacking out process was obtained. The results show that the jacking force-displacement curves of the three working conditions can be divided into two stages, and the jacking force reaches the maximum value at the moment when the static friction turns into sliding friction at the end of the first stage. The stress distribution at the bottom slab of the box culvert in the jacking process is approximately normal, and the stress decreases with the increase of the roadbed excavation thickness. The increase of the roadbed excavation thickness can reduce the soil pressure on the side of the box culvert and effectively reduce the deformation of the roadbed in the jacking-out process. The deformation of the roadbed during the jacking process can be reduced by increasing the thickness of the roadbed excavation.展开更多
CAD process for structure design of box culvert is introduced. It follows the traditional way of culvert design. All working conditions of culvert are taken into account. It can generate load diagram, bending moment d...CAD process for structure design of box culvert is introduced. It follows the traditional way of culvert design. All working conditions of culvert are taken into account. It can generate load diagram, bending moment diagram and bending moment envelope diagram for a single-hole, double-hole or triple-hole box culvert .That is to say, the whole CAD process for the box culvert structure design is realized with the self-developed system. It has been used to accomplish several projects in China and the results are satisfactory.展开更多
The uneven frost heave of frost-susceptible subgrade soil causes track irregularity,which highly enhances train vibration and affects the comfort and safety of railway transportation.This paper presents a coupled ther...The uneven frost heave of frost-susceptible subgrade soil causes track irregularity,which highly enhances train vibration and affects the comfort and safety of railway transportation.This paper presents a coupled thermo-hydro-mechanical(THM)analysis for the freezing behavior of railway located above a box culvert.The vertical acceleration of the vehicle,an indicator of riding comfort,is predicted through a vehicle dynamic model.The results reveal that the existence of a box culvert changes the subgrade thermal pattern,leading to a deeper frost penetration depth.The frost heave amount above the box culvert is larger than the adjacent section,resulting in uneven track structure upheave and track irregularity.This frostinduced track irregularity highly affects train vibration.展开更多
Blasting engineering in complex urban environments is considered to influence the safety and stability of the overlying drainage box culvert structure owing to vibration.Therefore,field blasting and vibration tests we...Blasting engineering in complex urban environments is considered to influence the safety and stability of the overlying drainage box culvert structure owing to vibration.Therefore,field blasting and vibration tests were performed on the blasting engineering of the Wuhan Metro Line 8 connected aisle,and the LS-DYNA software was used to analyze the dynamic response characteristics of an underground drainage box culvert during the blasting test.The vibration response evolution law of the buried drainage box culvert under blasting vibration was investigated,and a safe surface control standard for the blast vibration of a drainage box culvert is proposed.The results reveal that the maximum tensile stress of the box culvert structure was 0.33 MPa.The peak particle velocity(PPV)and peak tensile stress(PTS)of the drainage box culvert decreased as the water level in the box culvert increased.Based on the relationship between the tensile stress of the box culvert,PPV of the box culvert,and PPV of the surface,it is proposed that the surface control velocity of the buried drainage box culvert is 1.36 cm/s.展开更多
Japan has yet to establish a seismic design for road box culverts(RBCs)because past major earthquakes did not damage them.In recent years,structures with enlarged sectional dimensions(the purpose of which is to optimi...Japan has yet to establish a seismic design for road box culverts(RBCs)because past major earthquakes did not damage them.In recent years,structures with enlarged sectional dimensions(the purpose of which is to optimize the internal space in RBCs)have become common.However,the unknown seismic strength of such large RBCs makes RBC seismic designs increasingly necessary.Several seismic design methods have been developed for and applied to rectangular underground structures,e.g.,cut-and-cover tunnels,which are structurally similar to RBCs.Although these methods are applicable to RBCs,it is uncertain whether they can be applied directly because there are currently no evaluation results from model tests on RBCs,which have unique structural features,e.g.,no haunch at the bottom of the sidewalls.Therefore,we verify a seismic behavior of an RBC and develop a method for evaluating it in order to establish a seismic design for RBCs.We conducted centrifuge model tests subjected to seismic force and a numerical analysis using an elastoplastic finite analysis method,in addition,we validated this analysis by comparing the test and analytical results.The test results show RBCs will most likely develop rocking rotation when the ground strain exceeds approximately 0.08%.A comparison of the numerical and experimental results shows that this analysis can estimate the shear deformation behavior with approximately 90%accuracy in square cross-section cases.Meanwhile,this analysis has tendency to underestimate the axial forces in each case and to overestimate the bending moments of some members in the case of wide cross-sections.展开更多
基金Project(2012AA112504) supported by the National High Technology Research and Development Program of ChinaProjects(51108048,51478054) supported by the National Natural Science Foundation of China
文摘To obtain the vertical earth pressure on a soft foundation box culvert and investigate the interaction of the soil-culvert-foundation system, both a centrifugal model test and a numerical simulation were conducted and the comparisons with the current methods to determine the load on a culvert were completed. The results of the model test and numerical analysis are in satisfactory agreement, which shows that the direction of the shear stress between the culvert and the adjacent embankment depends on the differential settlement between them. A vertical earth pressure concentration appears on the culvert with a rigid piles foundation because of a downward shear stress. The ratio of the load on a soft foundation culvert and the overburden pressure above the culvert raises first and then decreases as the backfill height increases. In order to reduce the load on a culvert, it is suggested to limit the stiffness difference of the foundations under the culvert and embankment and to use a light backfill over the culvert.
文摘Studying the critical response characteristics of reinforced concrete box culverts with diverse geometrical configurations under seismic excitations is a necessary step to develop a reasonable design method. In this work, numerical analysis and assessment of reinforced concrete box culverts for seismic loading in addition to standard static loading from dead and live loads is conducted, aiming to highlight the critical difference in the seismic performances between two and three cell box culverts under near and far-fault ground motion. The results show how and where the seismic loading alters the responses of seismic loading of the models including the effect on safety and failure. The geometrical configurations of the culvert combined with the loading scenarios also significantly influence the magnitude and distribution of the seismic responses. The findings of this work shed light on the critical role of the geometrical configurations and shaking event in the seismic responses of reinforced concrete box culverts and this procedure can be applied as seismic assessment method to any culvert shape, size, and material.
文摘To shorten the existing box culvert demolition construction period and ensure the normal operation of the railway, the jacking-out construction method was adopted. The ABAQUS finite element software was used to establish a three-dimensional model of the box culvert and soil body of the relying project, and three excavation thickness (0m, 1 m, 2 m) were used as the main variation parameters for numerical analysis and research, and the change law of the box culvert itself and soil body stress during the culvert jacking out process was obtained. The results show that the jacking force-displacement curves of the three working conditions can be divided into two stages, and the jacking force reaches the maximum value at the moment when the static friction turns into sliding friction at the end of the first stage. The stress distribution at the bottom slab of the box culvert in the jacking process is approximately normal, and the stress decreases with the increase of the roadbed excavation thickness. The increase of the roadbed excavation thickness can reduce the soil pressure on the side of the box culvert and effectively reduce the deformation of the roadbed in the jacking-out process. The deformation of the roadbed during the jacking process can be reduced by increasing the thickness of the roadbed excavation.
文摘CAD process for structure design of box culvert is introduced. It follows the traditional way of culvert design. All working conditions of culvert are taken into account. It can generate load diagram, bending moment diagram and bending moment envelope diagram for a single-hole, double-hole or triple-hole box culvert .That is to say, the whole CAD process for the box culvert structure design is realized with the self-developed system. It has been used to accomplish several projects in China and the results are satisfactory.
基金supported in part by Grant-in-Aids for Scientific Research (A) (16H02360) and Research (C) (15K06214) from Japan Society for the Promotion of Science (JSPS) KAKENHI
文摘The uneven frost heave of frost-susceptible subgrade soil causes track irregularity,which highly enhances train vibration and affects the comfort and safety of railway transportation.This paper presents a coupled thermo-hydro-mechanical(THM)analysis for the freezing behavior of railway located above a box culvert.The vertical acceleration of the vehicle,an indicator of riding comfort,is predicted through a vehicle dynamic model.The results reveal that the existence of a box culvert changes the subgrade thermal pattern,leading to a deeper frost penetration depth.The frost heave amount above the box culvert is larger than the adjacent section,resulting in uneven track structure upheave and track irregularity.This frostinduced track irregularity highly affects train vibration.
基金sponsored by the National Natural Science Foundation of China(Grant Nos.41807265,41972286,and 42072309)the Hubei Key Laboratory of Blasting Engineering Foundation(Nos.HKLBEF202001 and HKLBEF202002).
文摘Blasting engineering in complex urban environments is considered to influence the safety and stability of the overlying drainage box culvert structure owing to vibration.Therefore,field blasting and vibration tests were performed on the blasting engineering of the Wuhan Metro Line 8 connected aisle,and the LS-DYNA software was used to analyze the dynamic response characteristics of an underground drainage box culvert during the blasting test.The vibration response evolution law of the buried drainage box culvert under blasting vibration was investigated,and a safe surface control standard for the blast vibration of a drainage box culvert is proposed.The results reveal that the maximum tensile stress of the box culvert structure was 0.33 MPa.The peak particle velocity(PPV)and peak tensile stress(PTS)of the drainage box culvert decreased as the water level in the box culvert increased.Based on the relationship between the tensile stress of the box culvert,PPV of the box culvert,and PPV of the surface,it is proposed that the surface control velocity of the buried drainage box culvert is 1.36 cm/s.
文摘Japan has yet to establish a seismic design for road box culverts(RBCs)because past major earthquakes did not damage them.In recent years,structures with enlarged sectional dimensions(the purpose of which is to optimize the internal space in RBCs)have become common.However,the unknown seismic strength of such large RBCs makes RBC seismic designs increasingly necessary.Several seismic design methods have been developed for and applied to rectangular underground structures,e.g.,cut-and-cover tunnels,which are structurally similar to RBCs.Although these methods are applicable to RBCs,it is uncertain whether they can be applied directly because there are currently no evaluation results from model tests on RBCs,which have unique structural features,e.g.,no haunch at the bottom of the sidewalls.Therefore,we verify a seismic behavior of an RBC and develop a method for evaluating it in order to establish a seismic design for RBCs.We conducted centrifuge model tests subjected to seismic force and a numerical analysis using an elastoplastic finite analysis method,in addition,we validated this analysis by comparing the test and analytical results.The test results show RBCs will most likely develop rocking rotation when the ground strain exceeds approximately 0.08%.A comparison of the numerical and experimental results shows that this analysis can estimate the shear deformation behavior with approximately 90%accuracy in square cross-section cases.Meanwhile,this analysis has tendency to underestimate the axial forces in each case and to overestimate the bending moments of some members in the case of wide cross-sections.
